1. Field of the Invention
The invention relates to an apparatus for treating tumors such as cancers or diseases such as benign prostatic hyperplasia by means of irradiating a vital tissue with a laser ray.
2. Description of the Related Art
A treatment technique has been known wherein a lesional region is shrunk or eliminated by alterating, sphacelating, coagulating, cauterizing and evaporating the tissue in the lesional region by means of irradiating it with a laser ray using a laser irradiation apparatus. The laser irradiation apparatus is long and slender and is left in a vital tissue by insertion into boy lumens such as blood vessels, urethra and abdominal cavity, or puncture of an organ, or a small discission.
In such a technique, the surface layer of a vital tissue or a lesional region in its vicinity is irradiated directly with a laser ray. In order to heat a lesional region located at a deep spot in a vital tissue to a sufficient temperature, it is required to apply a laser ray of a relatively large output. It may possibly involve a danger of damaging normal tissues such as a surface layer.
International Publication No. WO 93/04727 discloses a technique of coagulating and shrinking tumors or a portion of the prostate by means of the laser irradiation. This technique uses a balloon, through which cooling liquid is circulated, to cool the tissue to be protected. However, because the laser emitting unit is fixed, the laser power has to be limited, which results in the inconvenience of the reatment being too long.
Unexamined Publication No. JP-A-6-154239 discloses a laser irradiation apparatus to be inserted into the urethra in order to treat benign prostatic hyperplasia. The apparatus includes a plurality of irradiation units to be placed at different positions. The laser rays irradiated from these irradiation units simultaneously converge on a target site in a deep lesional region to generate a sufficient amount of heat to shrink the lesional tissue. The temperatures of the vicinities of the target site are higher than the regions where the laser rays do not overlap. However, since paths of the laser rays are fixed, a certain region is created in the vicinity of the surface layer of the urethra where the laser rays do not overlap but the temperature is slightly higher. This phenomenon disadvantageously affects the protection of the surface layer of the urethra. Thus, the apparatus is not perfect from the standpoint of treating only the deep lesional region while minimizing the damage to the surface layer.
In a broader sense the object of the invention is to provide an apparatus capable of effectively irradiating a deep lesional region with a laser ray while preventing damages to the normal tissue to be protected easily and securely.
It is more specific object of this invention to provide a laser irradiation apparatus including a long and slender main body, an optical fiber, a drive unit, and a reflector. The optical fiber provided is slidable inside the main body, and has a proximal end through which a laser ray is introduced and a distal end through which the laser ray is emitted. The drive unit causes the optical fiber to reciprocate in a longitudinal direction of the main body. The reflector is connected to the optical fiber and has a reflection plane for reflecting the laser ray emitted from the distal end of the optical fiber for reciprocating together with the optical fiber. The reflection plane changes its reflecting angle in accordance with the reciprocating motion of the optical fiber.
The objects, features, and characteristics of this invention other than those set forth above will become apparent from the description given herein below with reference to preferred embodiments illustrated in the accompanying drawings.